Radiator bleed valve / bolt

XJ-S
1

The bleed valve on the top left of my radiator is leaking. I found out from Kirby’s book that the size should be 1/8" BSPP, but the original valve is difficult to come by (part number C45587).

My question is if anyone knows which conversion to a normal European size bolt would be possible? I’ve tried to decipher conversion charts but I’m getting nowhere. Or does anyone know where to find an original bleed valve? I have no preference for a normal bolt or the orginal bleed valve, as long as it stops leaking. I’ve contacted local used part retailers here in Holland but no-one seems to sell them!

BleedPlugs

(Pictures from the old .org forum)

2

Unless the threads are bad, a good copper washer is the seal. Make sure radiator surface is smooth.

3

If leak due to bad VALVE, go to proper Plumbing/ hardware store and buy brass PLUG, as newer cars had. Bring in your valve and or specify thread. Alternate- fill valve with epoxy (or braze shut) , and treat as plug.

4

Try doing a Google search for 1/8 " radiator bleed valve

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5

Good suggestion. Is there a standard size to it or could I just fit an universal one?

6

Thanks for your reply, I’ll have look next week. Plan B is to fill it with epoxy indeed

7

In USA- it is a very odd pet-cock, as we are UNP, straight-odd, or Taper- common. . You know thread, and have sample. That is why PLUG is advice for quick solution, cheap.

8

Mine isn’t quite 3/8-24; however, it fits M10-1.00 very nicely.

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9

We just fitted a domestic central heating radiator bleed valve in the hole same thread and easy square key

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10

So I’m a bit confused, are the pre HE different than my HE?

Mine looks like a simple bolt. No tapered threads. Getting it snug with a new copper washer makes it leak free for me. I change washer every time i need to bleed.

11

Greg. I don’t know about the pre HE.
I do know that my 95 v12 had straight threads and copper washer. Had to replace the radiator and the new aftermarket had tapered thread plug.
I eventually replaced that one with an aluminum radiator from Wizard Cooling

12

Greg, that photo was of the “simple bolt” top radiator/cooling system bleed bolt in my 83 HE V12. The photo was just showing that, size and thread pitch, it very nicely fits in the M10-1.00 threaded hole.

It may be some “special” British size/thread as it was not UNF … close, but as Groucho Marx said “close, but no cigar”.

Not a bleed valve, just the bolt to remove.

No tapered threads, just copper washer to seal.

13

Be careful if your solution sticks up a bit. I have a pimple bump in the bonnet from using a taller banjo bolt/spacer setup on the RH side. Oops. Clearance is pretty tight above the radiator.

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14

Thanks for all the suggestions everyone! Appreciate it. I’ll get to work on it soon!